ABSTRACT: Bonamia ostreae is a haplosporidian parasite of oysters that was first reported to occur in the Southern Hemisphere in 2015 in the New Zealand flat oyster Ostrea chilensis. Until that report, B. ostreae had been restricted to populations of O. edulis within the Northern Hemisphere. This large range extension raised questions regarding B. ostreae dispersal, including whether B. ostreae is a recent introduction and from where it originated. The whole 18S rRNA gene of New Zealand B. ostreae revealed 99.9-100% sequence homology to other published B. ostreae 18S rDNA sequences. Internal transcribed spacer (ITS) rDNA sequences (n = 29) were generated from New Zealand B. ostreae and compared to published B. ostreae sequences from 3 Northern Hemisphere sites: California, USA (n = 18), Maine, USA (n = 7), and the Netherlands (n = 6) to investigate intraspecific variation. Low ITS rDNA variation was observed from New Zealand B. ostreae isolates, and high levels of variation were observed from Northern Hemisphere B. ostreae sequences. We hypothesise that the low ITS rDNA diversity found in New Zealand B. ostreae is the result of a founder effect resulting from a single introduction from a limited number of propagules. The high level of ITS rDNA variation from the Northern Hemisphere prevented inferences of dispersal origins. New Zealand B. ostreae were genetically differentiated from all sites, and additional genetic data are required to better determine the origin of B. ostreae in New Zealand.

中文翻译：

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新西兰Bon鱼内部转录间隔子rDNA的内部变异低：最近到来的证据。

摘要：Bonamia ostreae是牡蛎的单倍体寄生虫，2015年首次报道其在南半球的新西兰牡蛎扁平牡蛎中发生。在该报告之前，B。ostreae仅限于北半球的可食O. edulis种群。这种大范围的扩展提出了关于B. ostreae扩散的问题，包括B. ostreae是否是最近引进的以及起源于何处。新西兰B. ostreae的整个18S rRNA基因与其他已发表的B. ostreae的序列同源性为99.9-100％18S rDNA序列。内部转录间隔子（ITS）rDNA序列（n = 29）是从新西兰B. ostreae生成的，并与来自北半球3个站点的公开B. ostreae序列进行了比较：美国加利福尼亚州（n = 18），美国缅因州（n = 7）和荷兰（n = 6）调查种内变异。从新西兰B. ostreae分离株中观察到低ITS rDNA变异，从北半球B. ostreae序列中观察到高水平的变异。我们假设在新西兰B. ostreae中发现较低的ITS rDNA多样性是有限数量的繁殖体一次导入所产生的奠基者效应的结果。来自北半球的ITS rDNA的高水平阻止了对传播起源的推断。新西兰B. ostreae在所有地点都有遗传差异，需要更多的遗传数据才能更好地确定B. ostreae在新西兰的起源。